1. Field of the Invention
This invention relates to a recording liquid suited for ink-jet recording which is performed by ejecting ink droplets from a recording head through its orifices, or for other recording by means of a writing tool such as a pen.
2. Description of the Prior Art
Ink-jet recording generates less noise and permits a high speed recording on plain paper without the necessity for any special fixing treatment, so that various types of ink-jet recording systems are being investigated energetically.
The recording liquid used for these ink-jet recording systems needs to fulfill the following requirements such that its physical properties such as viscosity, surface tension, etc. should be each within a proper range, it should not clog a fine spout (orifice), it should form images of bright color tone and of sufficiently high optical density, and it should not undergo a change in physical properties or deposit solid matter, during storage.
In addition, the recording liquid is desired to meet the following requirements as recording therewith should be accomplished without particular restriction of the kind of recording medium, including paper, which is the most typical recording medium, it should exhibit a high rate of fixing on recording media, it should give images excellent in resistances to water, solvent (particularly alcohol), light, and attrition, and it should form images with a high degree of resolution.
Since the recording liquid used for ink-jet recording is composed basically of a coloring component dye and its solvent, the above performance characteristics required are much affected by inherent properties of the dye. Accordingly, it is very important in the art to select a dye so as to provide the recording liquid with the above performance characteristics.
The solubility of the dye in the liquid medium is particularly important; it is essential for maintaining a good anti-clogging property and solution stability of the recording liquid that the dye be sufficiently soluble in water as well as in the wetting agent used, which is generally composed of an organic solvent.
On the other hand, for forming full-color images in ink-jet recording, the recording liquids containing three primary colors (magenta, yellow and cyan) or four primary colors (magenta, yellow, cyan and black) are used, wherein the color tone of a recorded image is governed by subtractive mixing of these recording liquids. In order to form images of desired color tone, these recording liquids are required to have ideal hues of primary colors, as magenta, yellow and cyan, respectively, and a high degree of chroma. Therefore, the proper selection of dyes taking the hues of recording liquids into consideration is also very important in the art.
However, almost none of the existing recording liquids of cyan color, in particular those containing a phthalocyanine dye as a coloring component, satisfy the above noted requirements, particularly with respect to the solubility and the color. Thus, a cyan color recording liquid meeting the above requirements has been strongly desired.